Lens.



L..W. BUGBEE.

LENS. APPLICATION FILED :uw 2a, 1915.

1,199,343.v Patentdsept. 26,1916.

Southbridge,`

UNITED strATEs rA'rENfr onirica..

LUCIAN W. BUGBEE, 0F SOUTHBRIDGE, MASSACHUSETTS, ASSIGNOR TO AMERICAN OPTICAL COMPANY, OF SOUTHBRIDGE, 'MASSACHUSETTS, A CORPORATION OF MAS- SACHUSET'IS.

LENS;

Specification of Letters Patent.

To all 'whom t may concern v l Be it known that I, LUciAN Prieen, a citizen of the United States, residing at and State of Massachusetts, have invented iication. 4

This invention relatesto 'lenses having a multiplicity of foci, andv is adapted primarily as a corrective lens for the vision, although it may be used and found equally efficient for other purposes as well.

The principal object of the invention is to provide a lens having a distance portion,

- a reading portion Vand an intermediate porrefraction from the remaining blanks, thusj tion, and to so form the Vlens as to arrange the distance portion at the upper part of the lens in the field of general vision, lthe intermediate portion at the lower part of the lensl as the desirable position for use in going between the aforemensity of casting the head or eyes to an unnatural position when reading, as has been the previous common practice.

Another object is Ato provide a multifocal lens composed of but two parts, there'- by providing a lens of this character which the cost of manufacture will not be appreciably increased over the cost ofmanu.- Ifacture of the ordinary ybifocal form of ilens.

Another obJect is to provide a multifocal lens in which but. one`of the blanks composing the'leiis hasa different index of obviatingthe necessity of the provisionpf other than the ordinary I crown and int forms of glass.

With the foregoing and other objects in view' the invention consistsin the novel features, of construction, combination andarrangement of partslas will be hereinafter more fully described, illustrated inthe aocompanying drawings and claimed.

lIn the drawings: Figure I is a sectional view through a two piece multi-focal lens constructed in accordance with the invenf tion.v Figi II is a similar view througha slightly modified formof lens; F-ig. `III is a face view of either of the structures illus- A mad' in Figs.: i` and ii;

1 Referring to the drawings by numerals,

in the county of lVorcester upl or down steps or' the like, andthe reading portion tioned portions so as to relieve the neces- Patented sept. 26, 1916.

particularly to Fig. I,`w`herein is illustrated l segment, the material of the-segment hav. certain new and -useful Improvements in I Lenses, of which thel following is a speciing, as is usual, a different index' of refracbe of the ordinary construction commonly used in the manufacture of bifocal lenses, and may be united in any preferred manner.-

As shown the segment is arranged upon' the outer face of the blank 1, to one side thereof, and extends inwardly ofthe blank a distance approximately one-half the width of the blank. In the formation of the improved multi-focal lens the outer or convex faces of the blank and segment are I ground toA any desired correctiveI curve, as

shown at 3. So far the lens is of the same form as is commonly used in the manufacture of bifocals, the only diHerence being that-the segment Q is relatively larger than ordinarily used. i i l Upon the inner or concavevface of the bla-nk l1 a curve- LLis ground, obliquely toV the curve ofthe inner 'face of the blankso as to include approximatelyone-half of the' segment 2. It will thus be seen that all of the material ofthe blank 1 is cut away from the blank 2 at its lower portion and- -that the inner. face of the blank 2 isformed into `a .curve 'corresponding with the curve ,formed upon the inner'face df the blank 1.

As before stated, the blank 2 is of a dierent index of refraction from the blank 1 and, therefore, the curves of the two blanks being the same it. will be understood that e'achof' the blanks will .have different focal powers, the segment'Q usually being of a higher index of refraction than thefblankl 1'-'and, therefore, the lower portion of the blank2 will be of a slightly higher focal power than thebla'nk The curved fusedponnection 4between the blanks'l and 2, 'together with thegdiiference in refractive index between the two blanks .serves to provide 'a relatively strong lens throughout the extent` of their fused connection. It lwill thus be seen that the distance between a' and b in Fig. I will bethe Idistance portion ofthe lens', the distance between b anda= will be the reading'portioii, or` strongest portion of the lens,and theddistance between c and d willv be' the intermediate or the termediate portions.

difference in refractive index between the two parts of-.the lens, the curve 4 being ground into the se ent 2 throughout approximately one-ha f its length so that the distance between b and c and c and d will be substantially equal.

In Fig. II of th drawings I have illustrated another manner' in which a trifocal lens may tion arranged between the distance and in- This lens comprises a blank l" and a segmentpQ which are of the same construction as set forth in connection with Fig. I of the drawings. Instead of grinding the lens as set forth in connection with Fig. I, however, a recess 5 is formed in the segment 2 at the lower portion thereof, and this recess has fused thereinto a second se ent 6 which may be of the same or of a di erent index of refraction from the blank 1, the fusing of the blank 5 into the segment serving to provide an intermediate portion at the lower part of the lens while the reading portion will be arranged between the intermediate and the' distance portions, as will be understood.

It is thought that the construction and advantages of the improved lens will be readily apparent to those sln'lled in the art to which the invention appertains, and while I have hereinishown and described certain eciic "manners of accomplishing the result esired I do not wish to be limited thereto except vto such limitations as the claims may import.

l I claim: y

1. A multi-focal lens including a distance portion, a reading portion and an intermediate portion, said reading portion being arbe formed having the reading por` ranged between the distance portion and the intermediate portion.

2. An ophthalmic lens including a distance portion, a4 reading portion and anV in- A' termediate portion, the intermediate portion I being arranged at the lowermost portion of the lens, the distance portion being arranged at the uppermost portion of the lens, and the reading portion-being arranged between the intermediate and distance portion. 1

v3. A lens comprising a blank having a rel cess formed therein, a segment fused'in said recess, the face of the lens opposite to said segment being ground away to exposea pordex, a lower portion of a different index, and

an intermediate portion formed by overlapping the material of the upper and lower portions. v p

5. A trifocal lens formed from two'pieces of glass of different indices of refraction and .comprising an upper portion of one index, a lower portion `of a diierent index, and an intermediate the material tions, one of said portions having a concave recess formed in the overlap thereof and the other portion having a convex' surface fitting in the recess.

In testimony whereof, I aix my signature in presence of two witnesses. LUCIAN W. BUGBEE.

Witnesses:

EDITH M. -HALvolasEN,4 JOSEPH J. DEMERS.

portion formed by .overlapping j of the upper and lower por-- 

